Support beams may be used in numerous structures and assemblies, such as containers, shipping containers, storage structures and temporary dwellings. In the case of shipping containers, the support beams, and in particular the lower support beams, typically provide support for both floor and wall components, and indirect support for ceiling components as their weight is transferred down through the wall components. In addition to providing support for floor and wall components, the lower support beams, and in particular the longitudinal lower support beams generally must also provide or be fitted with a means of lifting the shipping container, such as apertures for lift forks and/or lifting straps. Still further, the lower support beams of a shipping container must also provide support for the weight of items stowed within the container.
To maintain the structural integrity of the shipping container, the lower support beams, and in particular the lower longitudinal support beams, are also required to exhibit a minimum of deformation (e.g., vertical and/or torsional deflection) between loaded and unloaded states. If the lower support beams undergo, for example, vertical and/or torsional deflection between loaded and unloaded states, the sidewalls, floor and ceiling components may move relative to each other resulting in opening of sidewall, floor and/or ceiling seams, thus exposing the contents of the container to external elements, such as rain, snow, sea water, insects and rodents.
To meet the numerous requirements discussed above, lower support beams are typically fabricated from materials such as metal and/or wood. Support beams fabricated from metal and wood, while typically sturdy, can be undesirably heavy, requiring increased fuel costs associated with transporting the shipping container. In addition, metal support beams are subject to rusting, and wood beams are subject to rot, and as such must typically have protective coatings applied thereto. Due to the extensive and often rough handling that shipping containers undergo, coatings applied to lower support beams are usually quickly worn off, exposing the underlying beam substrate to degrative environmental conditions that may lead to rust and/or rot.
Support beams may be fabricated from plastic. In order, however, to meet weight support and minimal deflection requirements, plastic support beams typically have a weight that is similar to, if not greater than, that of the metal and wood beams they are designed to replace.
It would be desirable to develop a molded support beam that provides a desirable combination of light weight and high strength. In addition, it would be desirable that such newly developed molded support beams also possess sufficient dimensional stability, so as to provide a minimum of deformation between loaded and unloaded states.